Nope.
Which gas for the 6.2L
- Thread starter DStockton
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Nope.
Even on stock tuning, you should run nothing less than 89.
I went to 89 for two tanks and the tick is gone. So maybe something to it there. On the GM is out to nickel and dime everybody and f@ck you over comment, if that is how you feel why do you buy their product?? A Yukon Denali is $60-$65k, a Toyota sequoia is $60-$65, an armada platinum is $60-65' a expedition limited is $60-$65.....see where I am going here? Why would you give someone $60k of your money if you thought they were out to f@ck you over? I guess since a good friend of mine owns the GMC dealer I am willing to, in good faith, give him the benefit of the doubt. If I get f'd over,so be it, back to Lexus or Benz I will go. BTW, the extra 9 months of Sirius xm nav traffic and all that and the upgrades that GM and ford have made to warranty coverages in the last few years is to go after the import and luxury buyer.
Weird.. Mine is.
There is the same quote from the owners manual on mine too. A "recommended" fuel. I have only had a vehicle state in the manual "unleaded only" or "premium only". This what ever fuel you want should be cleared up. So I will put 91 in knowing it runs fine on 87.
Kenric
Member
I've been over this several times at work.
You can run 87 octane with absolutely no risk to your warranty. I'm fact, the only thing you really have to watch out for is getting ahold of high ethanol fuel in a car that is not flex fuel rated (with a fuel composition sensor). They will test your fuel if they suspect a problem and if you have a high Ethanol content you may be in trouble. Same goes with water and other contaminates.
Those engines have knock sensors that can sense the tinyest beginnings of knock before you could even sense it and automatically compensate for higher or lower octane fuel on the fly by adjusting spark timing.
However, unlike many cars, since the engine has a naturally high compression ratio, a knock sensor, and a fuel composition sensor, it really will take advantage of higher octane fuel and will increase power and fuel economy.
This is why premium is recommended but not required.
In fact, with modern engine controls, unless it is a boosted engine, it's pretty rare for cars to actually require premium anymore.
If you really want to maximize power and economy, find some premium that doesn't have any ethanol in it. It used to be that some of the highest octane fuels were ethanol free but anymore it is getting hard to find pure gasoline. There are web sites to help you locate pure gasoline.
You can run 87 octane with absolutely no risk to your warranty. I'm fact, the only thing you really have to watch out for is getting ahold of high ethanol fuel in a car that is not flex fuel rated (with a fuel composition sensor). They will test your fuel if they suspect a problem and if you have a high Ethanol content you may be in trouble. Same goes with water and other contaminates.
Those engines have knock sensors that can sense the tinyest beginnings of knock before you could even sense it and automatically compensate for higher or lower octane fuel on the fly by adjusting spark timing.
However, unlike many cars, since the engine has a naturally high compression ratio, a knock sensor, and a fuel composition sensor, it really will take advantage of higher octane fuel and will increase power and fuel economy.
This is why premium is recommended but not required.
In fact, with modern engine controls, unless it is a boosted engine, it's pretty rare for cars to actually require premium anymore.
If you really want to maximize power and economy, find some premium that doesn't have any ethanol in it. It used to be that some of the highest octane fuels were ethanol free but anymore it is getting hard to find pure gasoline. There are web sites to help you locate pure gasoline.
undy
Full Access Member
New guy here with a lot of automotive experience (degree in automotive technologies) and a lot of high performance engine building.
The thing about detonation (from low octane fuel) is that damage can still occur even though one doesn't hear an audible knock or ping. You can't always count on the PCM/ECM to repeatedly pull timing and prevent engine damage, even on the 6.2. Over a period of time engine damage becomes more and more of a "possibility". Hypereutectic pistons are very hard but very brittle too. Busted ring lands is the typical failure.
Having said all that, I'm picking up my new 13 Denali today (hopefully) and this is also a concern for me. I really don't want to be strapped with premium on a utility vehicle like this so this is my plan...
I'm going to hook-up HPTuners to my Yukon and run a data log utilizing 87, 89 and 93 octane fuels. I will monitor KR (knock retard) while driving under various situations and loads. If 87 octane causes repeated timing pulling then I'll move up to the octane that doesn't cause KR.
I will post up my findings once I do this...
Dave
The thing about detonation (from low octane fuel) is that damage can still occur even though one doesn't hear an audible knock or ping. You can't always count on the PCM/ECM to repeatedly pull timing and prevent engine damage, even on the 6.2. Over a period of time engine damage becomes more and more of a "possibility". Hypereutectic pistons are very hard but very brittle too. Busted ring lands is the typical failure.
Having said all that, I'm picking up my new 13 Denali today (hopefully) and this is also a concern for me. I really don't want to be strapped with premium on a utility vehicle like this so this is my plan...
I'm going to hook-up HPTuners to my Yukon and run a data log utilizing 87, 89 and 93 octane fuels. I will monitor KR (knock retard) while driving under various situations and loads. If 87 octane causes repeated timing pulling then I'll move up to the octane that doesn't cause KR.
I will post up my findings once I do this...
Dave
Parthery
Full Access Member
I too have been dealing with the same conundrum.
My NBS '06 6.0 ran great with 87...and that's the habit I'd gotten into. Same with the 5.3 in the NNBS '08.
The '10 NNBS 6.2 is a different animal. I had a stumble at idle.....had the throttle body cleaned which didn't help. Ran a couple of tanks of 93 through it and the stumble seems to have disappeared. Switched back to 87 and it's back, though not as noticable.
The frustration I have is the owners manual clearly states that if you have VIN Code "F" you should run 87...yet I too have the sticker on the fuel door that recommends Premium. If GM recommends 87, I see no reason to waste the $$$ on 93. Around here it's $.30/gal x 26 gallons = $8 a tank x 5 tanks a month is $40. I'm not cheap, but I'm also not into needlessly wasting money.....
My NBS '06 6.0 ran great with 87...and that's the habit I'd gotten into. Same with the 5.3 in the NNBS '08.
The '10 NNBS 6.2 is a different animal. I had a stumble at idle.....had the throttle body cleaned which didn't help. Ran a couple of tanks of 93 through it and the stumble seems to have disappeared. Switched back to 87 and it's back, though not as noticable.
The frustration I have is the owners manual clearly states that if you have VIN Code "F" you should run 87...yet I too have the sticker on the fuel door that recommends Premium. If GM recommends 87, I see no reason to waste the $$$ on 93. Around here it's $.30/gal x 26 gallons = $8 a tank x 5 tanks a month is $40. I'm not cheap, but I'm also not into needlessly wasting money.....
Kenric
Member
For most of my life I have seen people running premium in their run of the mill 8.5:1 compression engines, without knock sensors, variable valve timing, etc. And they swear the car runs better.
Well, maybe it did, but probably not from the increase in Octane. I usually happens that the premium fuels have detergents or other additives that make the engine run better. Or, maybe it is less ethanol.
The fact is that if the engine is not designed to take advantage of it, higher octane fuel is usually a waste. With the possible exception of very high head temperatures and intake air temperatures, like you might see in Death Valley. But, barring those conditions, you should not get better economy, power, or durability just because of the higher octane.
Also, the required octane for a given engine configuration goes down as altitude goes up. So, even if it is hot, climbing the pass to Eisenhower tunnel on I-70 in CO should not require high octane fuel, when you are climbing from say, 8,100 ft to 10,000 ft. But climbing from Stovepipe Wells to Townes Pass in Death Valley from -150 to 5,500 feet and starting at 122F? Yeah, you just might need premium. Funny thing is that the gas station at Stovepipe Wells doesn't sell Premium. Even though they charge like $5/gal for gas.
Anyway, times have changed. Now, many cars have sensors and controls that will actually take advantage of a higher octane fuel and will increase engine parameters, like timing advance, if the car has premium fuel.
The ECM will increase timing until the first indications of knock is heard and then no more. And this IS the right amount of knock. I really shouldn't call it knock because it is just a sub audible precursor. The best economy will be had right at that point and it will not hurt the engine at all.
How this works is that the further you increase timing, and compression (effective compression can be affected by valve timing, which is where variable valve timing comes into play) higher the combustion temperatures. When you have high combustion temperatures the fuel is more prone to pre-ignight, causing ping or knock, depending on how severe.
Octane is simply a rating of how resistant to pre-ignition a fuel is. It is not measure of how much energy there is. All gasoline should have roughly the same energy content (that insidious ethanol does decrease the energy content depending on the percentage, but it also increases the octane rating of the gasoline/ethanol mixture).
Therefore, if you have a higher octane fuel, you can run a higher effective compression ratio, and more ignition advance without pre-ignition, which increases fuel economy and power.
If your vehicle has the equipment to take advantage of the higher octane fuel, it will run better (more efficiently, with more power) when you run higher octane fuel.
If your engine does not have this capability, then the octane increase of premium will not improve how the engine runs (again, as far as power and efficiency goes)
Premium fuel can make a low compression engine run better in other respects due to other additives and potentially less ethanol, but not because it has higher Octane.
So, if you have a car that can take advantage of higher octane fuel them premium is RECOMMENDED.
If you have a car that cannot the advantage of higher octane then they will not even mention anything but regular.
However, if you have a vehicle with high compression, where you cannot sense knock with enough accuracy to catch just the barest starting of pre-ignition, or with enough ECU speed to process the signals, and ingnition mogule/ECM enough speed to slew the engine timing fast enough (read fully solid state ignition here as no distributor could react fast enough), then premium fuel will be REQUIRED.
For example, when the high compression North Star engine came out, premium was required. Then, after the engine controls, sensors, and ECM speed increased, with the same engine, GM changed it to premium recommended.
It's a good thing that premium is recommended in these vehicles. It give you more flexibility.
With all this said, I run premium in my Denali.
On a percentage basis, premium is deal compared the old days, where it could be 20% or more than regular.
The only real bad development in recent years is that the refiners are pretty much using 10% ethanol now in even premium.
Regards,
Kenric
Well, maybe it did, but probably not from the increase in Octane. I usually happens that the premium fuels have detergents or other additives that make the engine run better. Or, maybe it is less ethanol.
The fact is that if the engine is not designed to take advantage of it, higher octane fuel is usually a waste. With the possible exception of very high head temperatures and intake air temperatures, like you might see in Death Valley. But, barring those conditions, you should not get better economy, power, or durability just because of the higher octane.
Also, the required octane for a given engine configuration goes down as altitude goes up. So, even if it is hot, climbing the pass to Eisenhower tunnel on I-70 in CO should not require high octane fuel, when you are climbing from say, 8,100 ft to 10,000 ft. But climbing from Stovepipe Wells to Townes Pass in Death Valley from -150 to 5,500 feet and starting at 122F? Yeah, you just might need premium. Funny thing is that the gas station at Stovepipe Wells doesn't sell Premium. Even though they charge like $5/gal for gas.
Anyway, times have changed. Now, many cars have sensors and controls that will actually take advantage of a higher octane fuel and will increase engine parameters, like timing advance, if the car has premium fuel.
The ECM will increase timing until the first indications of knock is heard and then no more. And this IS the right amount of knock. I really shouldn't call it knock because it is just a sub audible precursor. The best economy will be had right at that point and it will not hurt the engine at all.
How this works is that the further you increase timing, and compression (effective compression can be affected by valve timing, which is where variable valve timing comes into play) higher the combustion temperatures. When you have high combustion temperatures the fuel is more prone to pre-ignight, causing ping or knock, depending on how severe.
Octane is simply a rating of how resistant to pre-ignition a fuel is. It is not measure of how much energy there is. All gasoline should have roughly the same energy content (that insidious ethanol does decrease the energy content depending on the percentage, but it also increases the octane rating of the gasoline/ethanol mixture).
Therefore, if you have a higher octane fuel, you can run a higher effective compression ratio, and more ignition advance without pre-ignition, which increases fuel economy and power.
If your vehicle has the equipment to take advantage of the higher octane fuel, it will run better (more efficiently, with more power) when you run higher octane fuel.
If your engine does not have this capability, then the octane increase of premium will not improve how the engine runs (again, as far as power and efficiency goes)
Premium fuel can make a low compression engine run better in other respects due to other additives and potentially less ethanol, but not because it has higher Octane.
So, if you have a car that can take advantage of higher octane fuel them premium is RECOMMENDED.
If you have a car that cannot the advantage of higher octane then they will not even mention anything but regular.
However, if you have a vehicle with high compression, where you cannot sense knock with enough accuracy to catch just the barest starting of pre-ignition, or with enough ECU speed to process the signals, and ingnition mogule/ECM enough speed to slew the engine timing fast enough (read fully solid state ignition here as no distributor could react fast enough), then premium fuel will be REQUIRED.
For example, when the high compression North Star engine came out, premium was required. Then, after the engine controls, sensors, and ECM speed increased, with the same engine, GM changed it to premium recommended.
It's a good thing that premium is recommended in these vehicles. It give you more flexibility.
With all this said, I run premium in my Denali.
On a percentage basis, premium is deal compared the old days, where it could be 20% or more than regular.
The only real bad development in recent years is that the refiners are pretty much using 10% ethanol now in even premium.
Regards,
Kenric
Last edited:
D_R_C
Full Access Member
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I will only run premium is every gas powered engine I own including my lawn mowers.
Every vehicle that I tried running regular or even mid grade by being a tight *** the mileage and performance dropped.
My older vehicles (no knock sensors) pinged pulling grades, and the mileage dropped 1 - 1 1/2 mpg.
And undy is right you don't always detect pinging/knock even is these newer engines.
What happens is all of a sudden over a long period of time you have a lot of blue smoke bellowing out the exhaust. Burnt hole in the piston, usually when your on vacation (the worst time) & towing something.
My Denali's mileage and power dropped using mid grade, so for me it is well worth the LITTLE cost difference 26 cents a gallon between regular and premium and 13 cents a gallon between mid grade and premium.
I would rather my vehicles run and perform as good as they can, this is why I will only run Premium.
My Motor Home has a 80 gallon tank, I spend the extra cash using Premium, over regular which regular is recommended. Using regular my mileage is 4-4.5mpg=320-360 miles per tank using regular. Using Premium 5.5-6.0=440-480 miles per tank using premium.
IMO its well worth the cost difference.
In AZ regular 87 octane, mid grade 89, Premium 91
Also in AZ the fuel quality gas & Diesel is low.
Every vehicle that I tried running regular or even mid grade by being a tight *** the mileage and performance dropped.
My older vehicles (no knock sensors) pinged pulling grades, and the mileage dropped 1 - 1 1/2 mpg.
And undy is right you don't always detect pinging/knock even is these newer engines.
What happens is all of a sudden over a long period of time you have a lot of blue smoke bellowing out the exhaust. Burnt hole in the piston, usually when your on vacation (the worst time) & towing something.
My Denali's mileage and power dropped using mid grade, so for me it is well worth the LITTLE cost difference 26 cents a gallon between regular and premium and 13 cents a gallon between mid grade and premium.
I would rather my vehicles run and perform as good as they can, this is why I will only run Premium.
My Motor Home has a 80 gallon tank, I spend the extra cash using Premium, over regular which regular is recommended. Using regular my mileage is 4-4.5mpg=320-360 miles per tank using regular. Using Premium 5.5-6.0=440-480 miles per tank using premium.
IMO its well worth the cost difference.
In AZ regular 87 octane, mid grade 89, Premium 91
Also in AZ the fuel quality gas & Diesel is low.
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